Field of the Invention
The present invention relates to an aerodynamic control device and a helmet including the same.
Description of the Related Art
The present invention relates to an aerodynamic control device having a void opening attached to a helmet worn by a motorcycle rider and a helmet including the same.
The motorcycle riders are obliged to wear a helmet in the viewpoint of protecting a head portion in the event of an accident. Particularly, in a super high speed riding, such as Road Racing World Championship Grand Prix which is the top class category in the motorcycle road races as well as the motor sports by motorcycles, a careless movement of a helmet may distract the attention of a rider from his riding in the race. In order to ride the motorcycle at the higher speed, the aerodynamics of the helmet is also important as well as the aerodynamics of the motorcycle.
FIG. 1 diagrams the aerodynamic forces acting on the helmeted rider in his driving of the motorcycle. FIG. 1 also diagrams a relationship among drag, lift, and side force acting on the helmeted rider.
The forces acting on the helmeted rider are generally classified into three components, which are the aerodynamic pressure (drag) acted from the front side of the motorcycle, the side force caused by a crosswind, and the aerodynamic lift raising the helmet. Particularly, the drag (Drag: X) pressing the helmet from the front side of the motorcycle, the lift (Lift: Z) raising the helmet up, and the side force (Yawing: Y) acted on the helmet in the lateral direction (the rotation direction), become stronger as the motorcycle travels faster than the common driving on the public road.
The drag can be defined as the pressure caused by a fluid flowing in the opposite direction to the traveling direction of the motorcycle. That is, the drag can be defined as air resistance and hence is expressed as the resisting force which acts on the traveling motorcycle so as to drag it backward and disturbs the progress movement of it. Thus, a load of the drag applied to the neck portion of the rider becomes bigger as the drag becomes stronger, that is, the air resistance of the helmet increases and hence the drag causes the rider to be tired.
The side force can be defined as the force which rolls the helmet from side to side (Yawing) caused by the wind blowing from the lateral side of the motorcycle or generated when passing through a large oncoming vehicle. Such a side force affects the entire helmet worn by the rider and hence may cause considerable risk in some cases.
The lift can be defined as the force which acts in the direction perpendicular to the traveling direction of the motorcycle so as to raise the helmet up in the air. When the helmet is going to be raised from the rider's head due to the act of the lift, the attention of the rider is distracted and hence the rider may lose a driving stability in some cases.
The helmet worn by the motorcycle rider has been considered that the air resistance can be decreased as long as the helmet shape is generally streamline in order to suppress the air pressure (drag) as much as possible. When the helmet shape becomes a streamline one, the coefficient of air resistance air resistance becomes smaller, but it is problem that the lift increases so that the helmet is raised up. Thus, the current helmets have a tendency excessively that the helmet becomes a streamline shape in order to decrease the air pressure, and a rear spoiler is attached to a rear portion of the helmet in order to generate a down force which counteracts a lift, as well.
Japanese Patent No. 4311691 discloses a helmet in which a pair of wake stabilizers 10 having a flat side rectification surface 15 are symmetrically bilaterally disposed on a rear stream portion 9 of the shell, and a rear spoiler 12 is provided from a top portion 11 to a rear surface of the shell on the helmet 1, as well, in order to prevent the helmet 1 from being swung right and left and stabilize it in the wind (air stream) having a higher relative speed. Here, the wake stabilizer 10 guides the winds (air streams) flowing along both left and right side surfaces of the helmet 1 along the side rectification surface 15 to a rear position separated from the helmet 1 as much as possible. Further, the rear spoiler 12 suppresses the turbulence vortex or Karman vortex generated by the wind (air stream) flowing over the top portion of the helmet 1.
However, there is a limitation on the effect of decreasing the drag, the lift, and the side force at a high-speed traveling by the former rear spoiler attached to the rear surface of the helmet. Besides, as mentioned above, in a super high speed race, such as Road Racing World Championship Grand Prix, it is feared that the mild swing of the helmet may cause a large accident. Thus, there is an actual desire for an aerodynamic control device having higher aerodynamic performance and a helmet including the same.
Further, the wake stabilizer disclosed in Japanese Patent No. 4311691 can also prevent the helmet from being swung left and right to some extent against the wind (air stream) having a higher relative speed. Particularly, even a slight swing of the helmet is very dangerous in some races at a speed exceeding 300 km/h. Thus, the helmet which ensures safer and faster driving becomes an important article for a rider.
However, the flowing direction or the strength of the traveling winds acting on the helmet are substantially changed in accordance with the presence or not, the shape or, the size of the cowl (wind guard) equipped with the motorcycle with the intention of decreasing the air resistance or protecting the rider from the traveling winds. Since the function device, that is the wake stabilizer disclosed in Japanese Patent No. 4311691, is provided integrally as a part of the area forming the rear spoiler for suppressing the side force, when the motorcycle is equipped with a cowl among various kinds of cowls and then the motorcycle travels in a high speed range, there is a possibility that the wake stabilizer cannot manage the flow or the strength of the winds acting on the helmet. Thus, it cannot be said that the wake stabilizer is considered to improve the driving stability of the motorcycle under all circumstances in which the motorcycle can travel.